The Canarian shrew is classified as Endangered (EN) on the IUCN Red List (1) and is listed on Appendix II of the Bern Convention (3).

The Canarian shrew (Crocidura canariensis) is a tiny mammal with a small, endangered population residing exclusively on the easternmost Canary Islands, where it is the only native terrestrial predator (4).

In addition to its tiny size, the Canarian shrew can be recognised by its uniform chocolate brown fur (5). The fur on its back is a dark greyish-brown and the underside is also dark, but the hairs are whitish at the tips, making the fur appear dappled (2).

The Canarian shrew has large ears and a long tail, which is covered in whitish hairs (2) (5). The ears and the limbs appear lighter than the rest of the body, as these areas are also covered in fine, white hairs (2).

In contrast to several other members of the Crociduragenus, the Canarian shrew does not possess enlarged foreclaws (6).

The Canarian shrew is the only land mammal endemic to the Canary Islands (7), where it can be found on the eastern islands of Lanzarote, Fuertoventura, Lobos and Montaña Clara (1) (2). It has a fragmented distribution and only occurs in a very small total area of less than 5,000 square kilometres (1).

Fossil evidence indicates that the Canarian shrew was once prevalent on the islands of Graciosa and Alegranza, but as it has never been captured there it is assumed to be extinct (1) (4).

The Canarian shrew can be found in the “malpaís”, which are areas of barren lava fields with little or no vegetation (1) (2) (5). It uses lava tubes to protect it from the hot and dry conditions (1).

The Canarian shrew is also known to inhabit gardens and abandoned arable land near to the lava fields, as well as rocky and sandy areas. On Montaña Clara, it is limited to a single sand dune (1).

The Canarian shrew is very well adapted to the hot and dry conditions of the lava fields. In the malpaís, it uses lava tubes which provide a small amount of protection from the weather. This enables the Canarian shrew to survive even when surface temperatures approach 60 degrees Celsius (1).

The Canarian shrew feeds mainly on insects and snails within the lava tubes, but its diet varies between different populations. On Montaña Clara Island, in addition to sand fleas and seabird corpses, the Canarian shrew’s main source of food is the Atlantic lizard (Gallotia atlantica), a small lizard weighing less than seven grams (4).

Unusually for a mammal, the Canarian shrew uses venom to immobilise its prey. The effects on one its prey species, the Atlantic lizard, have been studied extensively (4).

When the Canarian shrew encounters an Atlantic lizard, it quickly attacks by jumping onto the lizardand biting its neck. The bite delivers neurotoxic venom, which very quickly immobilises the lizard, and paralyses it for 24 hours or longer. The Canarian shrew is capable of consuming the entire lizard, including its legs and innards, in less than an hour. However, if it has recently eaten, the Canarian shrew will carry away its prey and hide it among rocks to return to later. This is an important strategy in a challenging environment with unreliable resources (4).

The Canarian shrew is very secretive, and spends much of the day hidden under rocks, in a scratched-out cavity. However, it is capable of very quick and agile movement should it be disturbed. Surprisingly, the Canarian shrew is very quiet, with hardly any vocalisations observed from any experimentally studied specimens. This is in contrast to the closely related greater white-toothed shrew (Crocidura russula), which vocalises on many occasions (7).

Unlike other mammals of a similar size, the Canarian shrew produces small litters, usually of around one to three young. The gestation period is usually about 32 days (2) (7). The young Canarian shrew is born naked and blind and weighs approximately one gram. After 11 to 12 days, the young can walk, and it will continue to suckle up to about 23 days old. A Canarian shrew captured from the wild lived for five years in captivity (2).

Sadly, the Canarian shrew is an Endangered species, and the population on Montaña Clara consists of fewer than 100 individuals. This species is highly vulnerable due to its restricted distribution and specific habitat requirements (1) (2), and has already become extinct on the islands of Graciosa and Alegranza (4).

Habitat loss due to urbanisation around the Canarian shrew’s range is the most important and pressing threat to the Canarian shrew. In addition to this, the Canarian shrew population is also at risk due to predation by introduced feral cats (1).

As well as being listed on Appendix II of the Bern Convention (8) and Annex IV of the EU Habitats Directive (9), the Canarian shrew is protected under Spanish law and its range includes National Parks in Fuerteventura (1).

Recommended measures to conserve the Canarian shrew involve protecting its natural habitat and managing the populations of invasive species, such as feral cats, while preventing the introduction of further non-native species onto the small islands (1). Research is also required to find out more about the Canarian shrew’s requirements, to allow effective conservation strategies to be designed for this species (1) (2).

More information on the Canarian shrew:

Nowak, R.M. (1991) Walker’s Mammals of the World. The Johns Hopkins University Press, Baltimore and London.

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact: arkive@wildscreen.org.uk

Endemic: a species or taxonomic group that is only found in one particular country or geographic area.

Feral: previously domesticated animals that have returned to a wild state.

Genus: a category used in taxonomy, which is below ‘family’ and above ‘species’. A genus tends to contain species that have characteristics in common. The genus forms the first part of a ‘binomial’ Latin species name; the second part is the specific name.

Gestation: the state of being pregnant; the period from conception to birth.